The objective of this proposal is to continue our study on the detection and purification of antigen markers which may be useful in the diagnosis, prognosis, and therapy of prostate cancer. Several monoclonal antibodies have been produced having a spectrum of specificities against surface antigens on cultured prostate adenocarcinoma cells. One of the monoclonal antibodies, DU83.21, is to be evaluated for its clinical application. DU83.21 has been extensively characterized and demonstrated to bind to prostate and bladder carcinoma cells and to CMV (isolated from human prostate) transformed human embryonic lung cells. Further characterization of the specificities of other monoclonal antibodies directed against cultured prostate cell surface antigens will be determined. We will continue to use the lymphocyte hybridoma technique to produce monoclonal antibodies against prostate tumor antigens. Well-characterized adenocarcinoma cell lines and fresh prostate tumor tissue will be used as immunogens for mouse/mouse fusions. In addition, continued efforts will be made to establish hybridomas by fusing lymphocytes from prostate patient lymph nodes or spleen with mouse and human myeloma cell lines. The binding specificity to target cells will be measured by both direct and blocking assays (solid phase radioimmunoassay, membrane immunofluorescence, immunohistochemical, and cytotoxic assays) using a panel of cultured and fresh human normal and tumor cells. These same assays will also be used to determine the relationship of the antigens detected by the monoclonal antibodies to normal (e.g., HLA, Dr) and cancer markers (e.g., CEA, PAP, PA, fibronectin) associated with prostate cancer. The chemical nature of the antigens will be evaluated by immunoprecipitation and chromatographic methods and, finally, the antigens will be purified by affinity chromatography. the potential use of the purified antigens and monoclonal antibodies for diagnosis, tumor radiolocalization, and immunotherapy will be studied using: a radioimmunometric assay for measuring tumor antigens in body fluids; a nude mouse model for radioimmunological imaging tumors; in vitro cytotoxic assays and a nude mouse model for evaluating immunotherapy; and a nude mouse model for evaluating monoclonal antibodies for targeting therapeutic agents.